﻿/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2014 rocky, rockylin@qq.com
 *
 * 
 * NScheduler is free .NET library: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * NScheduler is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with NScheduler.  If not, see <http://www.gnu.org/licenses/>.
 *
 * NScheduler是一个自由.NET类库，您可以自由分发、修改其中的源代码或者重新发布它，
 * 新的任何修改后的重新发布版必须同样在遵守LGPL3或更后续的版本协议下发布.
 * 关于LGPL协议的细则请参考COPYING、COPYING.LESSER文件，
 * 您可以在NScheduler的相关目录中获得LGPL协议的副本，
 * 如果没有找到，请连接到 http://www.gnu.org/licenses/ 查看。
 *
 * - Author: Rocky Lin
 * - Contact: rockylin@qq.com
 * - License: GNU Lesser General Public License (LGPL)
 * - Blog and source code availability: https://lightso.codeplex.com/
 */
  

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Threading.Tasks;
using System.Configuration;

namespace NScheduler
{
    /// <summary>
    /// 后进先出队列,相同的任务提前处理
    /// </summary>
    public class DynamicStackScheduler : ConfigurationSectionGroup, IScheduler
    {
        protected List<Task> _queue;

        public DynamicStackScheduler()
        {
            _queue = new List<Task>();
        }

        public void Add(Task t)
        {
            Task oldTask = null;
            if (Contains(t, out oldTask))
            {
                _queue.Remove(oldTask);
            }

            _queue.Insert(0, t);
        }

        public void Remove(Task t)
        {
            _queue.Remove(t);
        }

        public bool Contains(Task t)
        {
            Task oldTask = null;
            bool found = Contains(t, out oldTask);
            return found;
        }

        public bool Contains(Task t, out Task oldTask)
        {
            bool found = false;
            oldTask = null;

            foreach (var task in _queue)
            {
                if (t.AsyncState != null && t.AsyncState.Equals(task.AsyncState))
                {
                    oldTask = task;
                    found = true;

                    break;
                }
            }

            return found;
        }

        public bool Contains(Task t, EqualityComparer<Task> comp)
        {
            throw new NotImplementedException();
        }

        public IEnumerator<Task> GetEnumerator()
        {
            return new SchedulerEnumerator(this);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return new SchedulerEnumerator(this);
        }

        public int Count
        {
            get { return _queue.Count; }
        }

        public Task this[int index]
        {
            get { return (Task)_queue[index]; }
            set { _queue[index] = value; }
        }
    }
}
